Rudder

Today, we are hiding exception stack in Rudder with the logback.xml config (the Ex{0} part):

<Pattern>%d{[yyyy-MM-dd HH:mm:ss]} %-5level %logger - %msg%n%xEx{0}</Pattern>

It may be that we did it because Java exception are really awful. But:

- the correct way to handle the problem of ugly exception is to carefuly handle all of them, not to hide them. If they are hidden, it is much harder to know that something is broken, whereas if we see the awful error, we want to handle it correctly. 
- that lead to completly impossible to debug errors: exception are rares, and they generally happen on specific context condition, hard to reproduced. So even if we try to display the exception again, it is not sure we will be able to. 
- user are used to Java exception. And we won't even imagine to hide for ex. Python stack trace. 
- there is rather few exception in Rudder (perhaps it was a time a where it was not the case, but not today anymore)

So for all the reasons, we should display exceptions.